Welcome to the Optseq Home Page

optseq2 is a tool for automatically scheduling events for
rapid-presentation event-related (RPER) fMRI experiments (the schedule
is the order and timing of events). Events in RPER are presented
closely enough in time that their hemodynamic responses will
overlap. This requires that the onset times of the events be jittered
in order to remove the overlap from the estimate of the hemodynamic
response. RPER is highly resistant to habituation, expectation, and set
because the subject does not know when the next stimulus will appear
or which stimulus type it will be. RPER is also more efficient than
fixed-interval event related (FIER) because more stimuli can be
presented within a given scanning interval at the cost of assuming
that the overlap in the hemodynamic responses will be linear. In SPM
parlance, RPER is referred to as 'stochastic design'.

The flexibility of RPER means that there are a huge number of possible
schedules, and they are not equal. optseq2 randomly samples the space
of possible schedules and returns the 'best' one, where the user can
control the definition of 'best'. Cost functions include: average
efficiency, average variance reduction factor (VRF), and a weighted
combination of average and stddev of the VRF. The user can also
specify that the first order counter-balancing of the sequence of
stimuli be pre-optimized.